I have a Chinese Pro Mini clone (keep going to type cloan for some reason) which I've successfully uploaded programs to with a USBASP programmer. I bought an FTDI programmer and was trying to use it yesterday with my NRF24L01 modules to watch the serial communications so tried programming with it too.
Serial comms works with it. No problems with that.
When I try and upload I get "not in sync: resp=0xe0". I read something about the bootloader so tried uploading that again with my USBASP and it said content mismatch after uploading and stopped working at all. Found out it needed a slower write speed for that so have to update the firmware on the USBASP so it would set the SCK, managed that with my Uno (also clone).
Got the bootloader fixed on the Pro Mini anyway, but after that if I tried to use the USBASP to upload sketches it said content mismatch. I could only upload at 16KHz. And the FTDI still doesn't work.
I also tried using my Uno as an FTDI programmer for it and it didn't work, same result. Tried changing the drivers (would they work with serial comms if they weren't working?)
Yeah, I just realised that's probably what I did last night. I have just uploaded the bootloader again though with the USBASP. FTDI still won't connect.
I had a new Pro Mini turn up today. Slightly different layout on the board. And guess what. The FTDI connected to it straight away, no pressing of reset, all 6 cables just plugged in the order I first had them and no problems at all. So it must be the other mini that is the problem.
Obviously with the DTR pin disconnected it does the same as the other Pro Mini, and I get not in sync 0x00. But I can press the reset button just after pressing upload and that also works.
Woo hoo. Got it working. I don't think the Arduino IDE properly burned the bootloader. I used AVRDude to do it instead and I now have both of them working.